Field of the Invention
The present invention relates to technology for manufacturing liquid microspheres in the fields of chemical industry, pharmaceutical, biochemistry and the like.
Description of the Background Art
There are conventionally known methods disclosed in International Publication WO 02/068104 A1 and Japanese Unexamined Patent Publication No. 2005-144356 as a method for manufacturing microspheres of another liquid (second liquid) in a specified liquid (first liquid). In the methods disclosed in these literatures, used is a microchannel, in which a continuous phase (first liquid) is flowed, and a dispersed phase (second liquid) is supplied to the flowing continuous phase in a direction intersecting with the flow of the continuous phase. The dispersed phase having entered the flow of this continuous phase is successively cut off by a shear force produced by the flow of the continuous phase, thereby forming microspheres considerably smaller than the channel cross section of the microchannel.
However, these methods have the following problems to be solved.
1) It is difficult to control the diameters of microspheres. The diameters thereof obtained by the above methods are likely to vary depending on various conditions, which disturbs stably manufacturing microspheres having a desired diameter. On this point, the above International Publication WO 02/068104 discloses that changing liquid feeding pressures of the dispersed phase and continuous phase enables the diameters of the microspheres to be controlled, but the pressure adjustments themselves are not easy. Conversely, the pressure variation during the operation causes an inconvenience of variation in the diameters of microspheres. On the other hand, the above Japanese Unexamined Patent Publication No. 2005-144356 discloses a control of microsphere diameters by changing an intersection angle of a dispersed phase introducing channel and a continuous phase introducing channel, but the particle diameters largely vary similar to the invention disclosed in the above International Publication WO 02/068104.
2) The facility cost of an apparatus is high. The above methods, which include cutting off the dispersed phase in the channel by the flowing force of the continuous phase in the channel, require a considerably large flow rate (flow rate of the continuous phase) to obtain a necessary shear force, and ensuring such a flow rate requires a relatively large liquid feeding facility (e.g. pump) and a driving power for it.